Class 7 Maths - WEST-BENGAL
Geometric Twins
The chapter Geometric Twins in the Class 7 Mathematics curriculum under the West Bengal Board of Secondary Education (WBBSE) introduces students to the fundamental concepts of congruence of geometric figures. Through this chapter, students learn how two figures are exact geometric twins if they have the exact same shape and size. We explore the criteria for congruence in line segments, angles, and triangles, specifically focusing on SSS, SAS, ASA, and RHS criteria for triangles. This chapter is crucial for building a strong foundation in geometry for board exams, helping students develop logical reasoning and spatial visualization skills necessary for solving advanced geometrical proofs later.
Start Learning FreeKey Concepts
Congruence
Congruent figures are geometric twins that have the exact same shape and size, meaning they can superimpose on one another completely.
Congruence of Line Segments
Two line segments are congruent if and only if they are of equal length.
Congruence of Angles
Two angles are congruent if and only if they have the exact same measure in degrees.
SSS Criterion
Side-Side-Side criterion states that two triangles are congruent if all three sides of one triangle are equal to the corresponding three sides of the other triangle.
SAS Criterion
Side-Angle-Side criterion states that two triangles are congruent if two sides and the included angle of one triangle are equal to the corresponding two sides and included angle of the other.
RHS Criterion
Right-angle-Hypotenuse-Side criterion states that two right-angled triangles are congruent if the hypotenuse and one side of one triangle are respectively equal to the hypotenuse and one side of the other.
Important Formulas
Board Exam Info
In the West Bengal (WBBSE) Class 7 annual mathematics examinations, the chapter Geometric Twins typically carries around 6 to 10 marks. Common question types include identifying congruent figures, filling in the blanks regarding congruence criteria (like SSS or SAS), proving triangle congruence in short answer questions, and drawing congruent line segments or angles.
Frequently Asked Questions
What is the difference between similarity and congruence?
Congruent figures are geometric twins having the same shape and exact same size. Similar figures have the same shape but can be of different sizes.
Why is the included angle important in the SAS criterion?
The included angle is the angle formed strictly between the two given sides. If the angle is not between them (SSA), the triangles may not be congruent.
How do we write the symbol for congruence?
The symbol for congruence is 'congruent', which is an equality sign with a tilde on top.
Learn Geometric Twins with Your AI Tutor
10 different ways to study this chapter. Free for 3 chapters per day.
Lecture
Key Points
Interactive
Quiz
Flashcards